The present disclosure relates to an optical fiber connector, for example an SC-style connector, and to a method of forming and using such a connector.
The mechanical tolerances involved in terminating single mode optical fiber are much tighter than those for multimode optical fiber. Therefore, while it is quite common for multimode optical fiber be terminated at the point of use, for example, at a user's premises or at an outside junction box, in most product applications, single mode optical fiber is not terminated in the field. When single mode fiber must be terminated in the field, then it can take a skilled technician between about 15 to 20 minutes to splice fibers together either by using a V-groove clamp or expensive fusion welding equipment.
Single mode fiber is therefore often provided in a range of different lengths, pre-terminated at both ends with a connector plug ready to plug into a matching receptacle. Commonly, eight or twelve single mode optical fibers may be bundled together in an optical fiber cable having an outer protective tube inside of which the optical fibers run.
An example of such a connector is the “Subscriber Connector,” or SC connector, originally developed by NTT®. SC connectors have convenient push/pull style mating, and are approximately square in cross-section and with a 2.5 mm diameter ferule at the termination of the optical fiber, surrounded by a plastic housing for protection. SC connectors are available in single or duplex configurations. The SC connector latches into a matching socket in a simple push motion. The push-pull design includes a spring against which the ferrule slides within a plastic inner housing. This arrangement provides a reliable contact pressure at the ferrule end and resists fiber end face contact damage of the optical fiber during connection. The connector can be quickly disconnected by first pulling back an outer housing, which is slidable relative to the inner housing, to disengage a latch inside socket between the socket and the inner housing, before pulling the optical fiber connector from the socket. Until the latch is thus disengaged, the latch prevents withdrawal of the connector when the optical fiber cable is pulled in a direction away from the socket.
A different type of optical fiber connector is the ST type connector, which has a key that prevents rotation of the ceramic ferrule and which connects with a socket using a bayonet lock with an outer shell. All such bayonet type optical fiber connectors are referred to herein for convenience as “ST-type” optical fiber connectors.
An advantage of the SC connector over this type of bayonet connector is that the connector sockets can be more closely packed, as there is no need to get fingers fully around the connector to disengage the connector from the socket.
Other examples of push/pull type connectors are LC connectors or MU connectors. Often, the fiber-end is angled to reduce back reflections and this is usually described by adding APC (Angled Physical Contact) to the name. All such push/pull type optical fiber connectors are for convenience referred to herein as “SC-type” optical fiber connectors. SC-type LC or MU connectors are also known as small form factor connectors, by virtue of having a 1.5 mm diameter ferrule and a plastic housing.
It is important to avoid bending optical fiber around curves having too sharp a bend radius, as this will increase optical losses and can permanently damage the optical fiber. Optical fiber cables are therefore often routed inside a protective outer tube or conduit, which can have minimum bend-limiting properties. Protective bend limiting conduits normally have an outer diameter of 8 mm or 10 mm tubes. The cross-section of a standard SC connector has dimensions of about 7 mm×9 mm, and even a small form factor SC connector is too large to fit inside the inner diameter of a typical protective conduit.
Conventional optical fiber connectors comprise a rigid pushable structure to allow for limited movement of the connector parts while being pushed down stretches of duct. However, due to their rigid structure, conventional optical fiber connectors suffer from signal degradation when weight is added to the cable and the connector while the connector is transmitting a signal.
It may be desirable to provide an optical fiber connector with improved signal transmission capability. As such, it may be desirable to provide an optical fiber connector with a structure that isolates the front end of the connector from the rear end of the connector such that the ferrule is isolated from movement when the rear end of the connector bends due to weight being added to the rear end.